At present there are known sealing devices of the above type in which a rubber gasket being integral with one of the races of the bearing engages in sliding contact the outer cylindrical surface of a bush mounted to the other race of the bearing. The bush is subjected to grinding operations as well as thermal treatment to render said cylindrical surface smooth enough to ensure satisfactory sealing action and not wear out the gasket quickly. These accurate operations involve costs that make it desirable to have other alternative solutions.
Another limit with said known prior art is that this kind of sealing device is not able of providing simultaneously hermetic sealing and a sufficiently low frictional torque. As known, with bearings the greater part of energy consumption is due to the sealing devices. Further, owing to suction effects, while sealing devices are capable of preventing leak of lubricant from the bearing, they are not so efficient in preventing water or other contaminants from entering the bearing, and vice versa.